Device for varying the valve control times of an internal combustion engine, especially a camshaft adjusting device with a pivotal impeller wheel

ABSTRACT

A hydraulic camshaft adjusting device, which comprises a drive wheel ( 2 ) and a pivotal impeller wheel ( 10 ) connected in a rotationally fixed manner to a camshaft ( 9 ), the drive wheel ( 2 ) comprises a. cavity formed by a peripheral wall ( 3 ) and two lateral walls, in which cavity at least one hydraulic working space ( 8 ) is formed by at least two delimitation walls ( 7 ) and the pivotal impeller wheel ( 10 ) has at least one radial blade ( 12 ), and with each blade ( 12 ) divides a hydraulic working space ( 8 ) into two hydraulic pressure chambers ( 13, 14 ), which are sealed off from one another by sealing elements ( 17 ) disposed between the drive wheel ( 2 ) and the pivotal impeller wheel ( 10 ), the pivotal impeller wheel ( 10 ) can be mechanically coupled to the drive wheel ( 2 ) in a preferred basic position, a locking element ( 18 ) disposed on the drive wheel ( 2 ) being movable by a spring clement ( 19 ) into a complementary seating ( 20 ) in the drive wheel ( 2 ).

DESCRIPTION

1. Field of the Invention

The invention relates to a device for varying the valve control times ofan internal combustion engine in accordance with the features formingthe precharacterizing clause of claim 1, and is particularlyadvantageously implementable on hydraulic camshaft adjusting deviceswith pivotal impeller wheel.

2. Background of the Invention

Such a device was generically disclosed by EP 0 845 584 A1. This device,configured as what is known as a pivotal impeller wheel adjustingdevice, comprises a drive wheel configured as an outer rotor anddrive-connected to a crankshaft of the internal combustion engine, whichdrive wheel comprises a cavity formed by a hollow cylindrical peripheralwall and two lateral walls, within which cavity four hydraulic workingspaces are formed by four delimitation walls starting from the inside ofthe peripheral wall and oriented toward the longitudinal central axis ofthe drive wheel. The device further comprises a pivotal impeller wheelconnected in a rotationally fixed manner to a camshaft of the internalcombustion engine and inset into the cavity of the drive wheel, and inturn having on the periphery of its wheel hub four radially disposed,solid blades, which each extend into a working space of the drive wheeland divide the latter into pairs of hydraulic pressure chambers workingin opposition to one another. The pressure chambers are sealed off fromone another by sealing elements disposed between the free end surface ofeach blade of the pivotal impeller wheel and the peripheral wall of thedrive wheel and between the free end surface of each delimitation wallof the drive wheel and the wheel hub of the pivotal impeller wheel and,when selectively or simultaneously subjected to the action of pressureby means of a hydraulic pressure medium, effect a pivot movement orfixing of the pivotal impeller wheel relative to the drive wheel andhence of the camshaft relative to the crankshaft. When the internalcombustion engine is switched off, moreover, the pivotal impeller wheelcan be mechanically coupled to the drive wheel, with minimization of thevolume of a pressure chamber of each hydraulic working space, in apreferred basic position for the starting of the internal combustionengine, a locking element configured as an axial locking pin beingdisposed within one of the radial blades of the pivotal impeller wheelor on the drive wheel and being axially movable by a spring element,configured as a helical compression spring, into a coupling positionwithin a complementary seating configured as an axial engagementaperture in a lateral wall of the drive wheel. The axial engagementaperture of the locking pin is hydraulically connected to the pressuremedium feed to a pressure chamber of a hydraulic working space of thedevice, in such a manner that when the internal combustion engine isstarted, as a result of the subjection to the action of pressure of onepressure chamber of the hydraulic working spaces, the engagementaperture of the locking pin is simultaneously subjected to the action ofpressure and as a result of action on its end surface located in theengagement aperture is moved hydraulically into an uncoupling positionwithin the blade of the pivotal impeller wheel.

A further possible form of mechanical coupling between the impellerwheel and the drive wheel of a hydraulic camshaft adjusting device isproposed by the solution disclosed in U.S. Pat. No. 4,858,572. Thisdevice, which is of the type known as a vane cell adjusting device andis comparable in structural terms with a pivotal impeller wheeladjusting device but differs therefrom in having lighter blades on theimpeller wheel and, in most cases, a larger number of hydraulic workingspaces, comprises a total of six hydraulic working spaces, of which thefirst three working spaces can be subjected to the action of a hydraulicpressure medium only in one direction of rotation and the second threeworking spaces only in the other direction of rotation. In this device,in contrast to the device described initially, the mechanical couplingof the impeller wheel to the drive wheel of the device in a preferredbasic position for the starting of the internal combustion engine iseffected by two locking elements configured as radial locking pins, eachof which is disposed in a radial bore in two mutually oppositedelimitation walls of the drive wheel. These radial locking pins arealternately movable by a spring element configured as a helicalcompression spring into, in each case, a complementary seating disposedbetween two blades in the wheel hub of the impeller wheel and configuredas a radial receiving bore, when the blades of the impeller wheel, inone of their two end positions, encounter the delimitation walls of thedrive wheel, and the first or second working spaces, when the internalcombustion engine is switched off, are no longer subject to the actionof the pressure of a pressure medium. The radial receiving bores of thelocking pins are hydraulically connected to the pressure medium feed tothe first three or the second three hydraulic working spaces in a mannersuch that, within a filling channel to each of the working spaces, theyare upstream of the latter in series, so that when the first three orsecond three working spaces are subjected to the action of pressure thelocked locking pin is first subjected to the action of pressure by thepressure medium against the force of its spring element and is movedhydraulically into an uncoupling position within the delimitation wallof the drive wheel, and filling of the hydraulic working spaces is onlysubsequently possible.

These locking elements, designed in one case as an axial locking pin andin the other as a radial locking pin, for mechanical coupling betweenthe impeller wheel and the drive wheel of a pivotal impeller wheel orvane cell adjusting device have, however, the disadvantage that they areformed from a plurality of individual parts which, in conjunction withnecessarily increased production and assembly effort, sometimessubstantially increase the cost of a pivotal impeller wheel or vane celladjusting device configured in this way.

OBJECT OF THE INVENTION

It is an object of the invention to design a device for varying thevalve control times of an internal combustion engine, especially acamshaft adjusting device, in which the mechanical coupling between thepivotal impeller wheel and the drive wheel can be achieved with aminimum number of individual parts and a low production effort, and theproduction and assembly costs of the device can thus be reduced to aminimum.

SUMMARY OF THE INVENTION

According to the invention, this object is achieved with a device inaccordance with the preamble of claim 1, in that at least one of thesealing elements between the pivotal impeller wheel and the drive wheelof the device is simultaneously configured as a locking element for themechanical coupling of the pivotal impeller wheel to the drive wheel ofthe device.

In an expedient further development of the invention, the pressurechambers of the device are preferably sealed off from one another onlyby sealing elements disposed between the free end surface of each bladeof the pivotal impeller wheel and the peripheral wall of the drive wheeland configured as conventional sealing strips or sealing rolls, of whichpreferably only one is simultaneously provided as a locking element.Such a sealing of the pressure chambers, in conjunction with theirfurther sealing by sealing joints between the free end surface of eachdelimitation wall of the drive wheel and the wheel hub of the pivotalimpeller wheel, has proven sufficient to meet requirements and, at thesame time, cost-effective, an arrangement, of further sealing elementsinstead of the sealing joints, for example further sealing elementsdisposed within an axial groove in the free end surface of thedelimitation walls, not being ruled out.

However, a particularly preferred embodiment of the sealing elementsbetween the free end surface of the pivotal impeller wheel and theperipheral wall of the drive wheel has proven to be radially movablesealing strips disposed in each case in an axial groove in the free endsurface of each blade of the pivotal impeller wheel and configured to beurged via supporting springs with a constant contact pressure againstthe inside of the peripheral wall of the drive wheel in order to improveleaktightness relative to the pressure medium. In this case, at leastthe sealing strip simultaneously configured as a locking element has, ina conventional manner, an axial length corresponding to the width of theperipheral wall of the drive wheel but differs from conventional sealingstrips disposed in axial grooves in the blades of a pivotal impellerwheel in having a radial height corresponding to approximately half thelength of a blade of the pivotal impeller wheel. To reduce the number ofdifferent components for the device, however, it is also possible andexpedient here to configure not only the sealing strip provided as alocking element but all sealing strips on the pivotal impeller wheel ofthe device in the manner described.

In another development of the invention, it is proposed, as a firstembodiment of a sealing strip locking system, to configure the sealingstrip simultaneously configured as a locking element to be axiallymovable in such a way that, in the coupling position, it is in positiveengagement, by one of its lateral surfaces oriented toward the lateralwalls of the drive wheel in one or more locking position(s) of thedevice, with, in each case, one radial fixing groove configured as acomplementary seating in the inside of one of the lateral walls of thedrive wheel. In most applications, it has proven sufficient here for thesealing strip simultaneously configured as a locking element to be inlatching connection with the drive wheel in only one locking position ofthe device, this one locking position preferably corresponding to one ofthe two end positions of the pivotal impeller wheel or, after the devicehas been installed on an input or output camshaft, respectively, tocorrespond to a camshaft twisted toward “late” or toward “early”. Thenecessary radial fixing groove of the sealing strip is, accordingly,preferably machined into the lateral wall of the drive wheel remote fromthe camshaft in the vicinity of one of the two delimitation walls of thehydraulic working space of the drive wheel divided by the blade with thelocking element and extending radially to the longitudinal axis of thedevice. Similarly, the scope of protection of the invention is alsointended to encompass those solutions in which two or more sealingstrips, or alternatively equivalently disposed sealing rollers, areconfigured as locking elements on the end surfaces of the blades of thepivotal impeller wheel, it being possible for all of these lockingelements either to be locked in one end position or alternatively, byproviding a further radial fixing groove within each hydraulic workingspace, to be locked in both end positions of the pivotal impeller wheel.It is also possible to configure one or more sealing strips to belatchable in one end position and one or more sealing strips to belatchable in the other end position of the pivotal impeller wheel,and/or, by providing additional identical radial fixing grooves in thehydraulic working spaces of the pivotal impeller wheel, alternatively tofix them in one or more position(s) between its two end positions ifparticular operating states of the internal combustion engine sorequire.

A further feature according to the invention of the first embodiment ofa sealing strip locking system is that the radial fixing groove in theinside of the lateral wall of the drive wheel remote from the camshafthas a length approximately corresponding to the height of the sealingstrip simultaneously configured as a locking element and is configuredto be slightly recessed over part of its length by a further pressuremedium guide groove, the non-recessed parts of the groove floor of theradial fixing groove being provided as axial stop surfaces of thesealing strip in its coupling position. The width of the radial fixinggroove, approximately corresponding to the thickness of the lockablesealing strip, is also so dimensioned that not only is easy sliding ofthe sealing strip into the fixing groove possible but also flapping ofthe sealing strip in its coupling position is prevented, and the lateralsurfaces of the fixing groove act as stop surfaces for the lockablesealing strip in both directions of rotation of the impeller wheel. Inorder further to facilitate the sliding of the sealing strip into theradial fixing groove, it is also advantageous additionally to chamfer orround off the lateral surfaces of the sealing strip or alternatively, asan equivalent measure, to configure the fixing groove to be slightlyconical in profile or to round off its edges. Similarly, it isadvantageous to make the lateral wall of the drive wheel remote from thecamshaft wear-resistant, at least in the region of the radial fixinggroove, in order to counteract the wear phenomena of the radial fixinggroove that necessarily occur as a result of continuous locking andunlocking of the device and the disadvantages resulting therefrom, suchas flapping of the sealing strips in their coupling position or thelike. This can be done particularly advantageously, in the case of adevice consisting of ferritic materials, by partial hardening of theregion of the radial fixing groove or by hardening of the whole lateralwall of the drive wheel remote from the camshaft, suitable coatings orsurface treatments also being possible here. In the case of a deviceproduced in the lightweight manner, in other words consisting ofnon-ferritic materials, by contrast, this can be effected in that theregion of the radial fixing groove is formed by a separate,prefabricated insert component in the lateral wall of the drive wheelremote from the camshaft, which consists of a wear-resistant materialsuch as, for example, a hardened steel or the like.

The pressure medium guide groove within the radial fixing groove is alsohydraulically connected at its end facing the longitudinal central axisof the device, via a pressure medium transverse groove machined in thelateral wall of the drive wheel remote from the camshaft, to a pressurechamber of the hydraulic working space of the drive wheel divided by theblade with the locking element. Through the pressure medium transversegroove, the hydraulic pressure medium passes, starting from an annularchannel in the wheel hub of the pivotal impeller wheel, via a pressuremedium feed line leading to the respective pressure chamber into thepressure medium guide groove within the radial fixing groove, so thatthe pressure acting on the part of the lateral surface of the sealingstrip that is not resting on the stop surfaces of the fixing groove inthe coupling position of the sealing strip, and is thus configured as apressure impact surface, effects an axial displacement of the sealingstrip into its uncoupling position if a particular pressure value isexceeded. It has also proven advantageous in this connection if thedelimitation walls of the drive wheel or the blades of the pivotalimpeller wheel each possess pressure medium pockets configured as freeincisions at their stop surfaces defining the locking position of thedevice, which accelerate the filling of the respective first pressurechambers to be subjected first to the action of pressure by a pressuremedium with the device locked in one of the end positions of the pivotalimpeller wheel and, by means of a virtually unhindered passing-on of thepressure-medium pressure via the pressure medium transverse groove ontothe pressure impact surface of the locked sealing strip, ensure a rapidand reliable axial displacement of the sealing strip into its uncouplingposition.

Finally, in the design according to the invention of the firstembodiment of a sealing strip locking system, it is further proposedthat two helical compression springs or conical springs, each disposedwithin an axial basic bore in the lateral surface of the sealing stripfacing the camshaft, are provided as the spring element for the axialmovement of the sealing strip configured as a locking element into itscoupling position and are each disposed within their basic bores toenclose a rivet-like guide pin which is in sliding spot contact with theinside of the lateral wall of the drive wheel facing the camshaft. Theseguide pins possess, at their ends facing the camshaft, a cross-sectionalthickening which can be recessed in their basic bores in the uncouplingposition of the sealing strip and by means of which the spring means canbe supported at one end on the floor of the basic bore and at the otherat the transition surface to this cross-sectional thickening. To reducethe friction between the guide pins and the lateral wall of the drivewheel during the adjustment operation, it is also advantageous toconfigure the end surface of each guide pin facing the camshaft in aconvex manner and in hardened form. Similarly, it has provenadvantageous to configure the guide pins, preferably, with a throughbore along their longitudinal central axis, which provides pressurecompensation and serves for easier displacement of hydraulic pressuremedium present in the basic bores during the movement of the sealingstrip into its uncoupling position.

In addition to the axial locking, described above, between the impellerwheel and the drive wheel by means of a sealing strip on a blade of thepivotal impeller wheel, in an alternative development of the inventionthere is also proposed, as a second embodiment of a sealing striplocking system, using the radially movable arrangement of the sealingstrips in the axial grooves in the end surfaces of the blades of thepivotal impeller wheel in such a way that the sealing stripsimultaneously configured as a locking element is in the couplingposition in positive engagement, by its sealing surface oriented towardthe lateral wall of the drive wheel in one or more locking position(s)of the device, with, in each case, one axial fixing groove configured asa complementary seating in the inside of the lateral wall of the drivewheel. In this embodiment also is has proven sufficient if the sealingstrip simultaneously configured as a locking element is in latchingconnection with the drive wheel in only one locking position of thedevice, this locking position likewise corresponding to one of the twoend positions of the pivotal impeller wheel lying on the delimitationwalls of the drive wheel. The axial fixing groove of the sealing stripis, accordingly, preferably machined into the peripheral wall of thedrive wheel in the vicinity of one of the two delimitation walls of theworking space of the drive wheel divided by the blade with the lockingelement. However, the scope of protection of the invention is alsointended to encompass those solutions in which two or more sealingstrips are simultaneously configured as locking elements, it beingpossible for all of these locking elements either to be locked in oneend position or alternatively, by providing a further axial fixinggroove in the vicinity of the respective other delimitation wall of eachhydraulic working space, to be locked in both end positions of thepivotal impeller wheel. Similarly, it is also possible here to configureone or more sealing strips to be latchable in one end position and oneor more sealing strips to be latchable in the other end position of thepivotal impeller wheel, and/or, by providing additional identical axialfixing grooves in the hydraulic working spaces, alternatively to fix thepivotal impeller wheel in one or more position(s) between its two endpositions if particular operating states of the internal combustionengine so require. In order to avoid, in this embodiment also, the wearphenomena of the axial fixing groove that necessarily occur and thedisadvantages resulting therefrom, it is likewise advantageous toconfigure the peripheral wall of the drive wheel to be wear-resistant,at least in the region of the axial fixing groove. This can again bedone advantageously in the case of a device consisting of ferriticmaterials by partial hardening of the region of the axial fixing grooveor by hardening of the whole peripheral wall of the drive wheel or,instead, by suitable coatings or surface treatments, while in the caseof a device produced in the lightweight manner this can be effected by aseparate, prefabricated insert component forming the region of the axialfixing groove, which consists of a wear-resistant material, for exampleof a hardened steel.

A further feature according to the invention of the second embodiment ofa sealing strip locking system is that the sealing surface of thesealing strip simultaneously configured as a locking element is slightlychamfered in the radial direction and is configured as a pressure impactsurface of the hydraulic pressure medium for the uncoupling position ofthe sealing strip, a separate pressure medium feed line being disposedto open into the widening gap between the sealing surface of the sealingstrip and the groove floor of the axial fixing groove, this separatepressure medium feed line being hydraulically connected to a pressurechamber of the hydraulic working space divided by the blade with thelocking element. The separate pressure medium feed line to the sealingsurface of the sealing strip configured as a locking element is in thiscase, in a preferred embodiment, configured as a unilateral or bilateraledge chamfering of the peripheral wall of the drive wheel which isdisposed to extend from the stop surface of one of the delimitationwalls of the hydraulic working space divided by the blade with thelocking element as far as the axial fixing groove. If the respectivepressure chamber is subjected to the action of pressure, therefore, thehydraulic medium, limited by the lateral walls of the drive wheel, flowsalong this edge chamfer to the chamfered sealing surface of the sealingstrip located in the axial fixing groove and effects a radialdisplacement of the sealing strip into its uncoupling position if aparticular pressure value is exceeded. As an alternative embodiment,however, it is also possible to configure the separate pressure mediumfeed line to the sealing surface of the sealing strip as a pressuremedium guide groove machined into the inside of the peripheral wall ofthe drive wheel, which likewise begins in the immediate vicinity of thestop surface of one of the delimitation walls of the hydraulic workingspace divided by the blade with the locking element and opens into theaxial fixing groove.

In a design according to the invention of this second embodiment of asealing strip locking system, finally, it is also proposed that thesupporting spring of the sealing strip, preferably configured as achimney spring or leaf spring, is provided as the spring element for theradial movement of the sealing strip configured as a locking elementinto its coupling position and is disposed to be supported at one end onthe groove floor of the axial groove for the sealing strip in the freeend surface of the blade of the pivotal impeller wheel and at the otherend on the end surface of the sealing strip facing the groove. Shouldits spring travel or spring force prove inadequate here, it is alsopossible, at least for the sealing strip configured as a lockingelement, to use helical compression springs or other suitable springelements recessed both into the groove floor of the axial groove in theblade and into the end surface of the sealing strip facing the groove,or alternatively to provide a plurality of different spring elementsconnected in series.

The device according to the invention for varying the valve controltimes of an internal combustion engine, especially a camshaft adjustingdevice, thus comprises the advantage compared with device known from theprior art, in both the embodiments described, that as a result of thedual function of a sealing element between the pivotal impeller wheeland the drive wheel as a simultaneous locking element only a minimum ofadditional individual components and additional effort in the productionof the device are required in order to be able to effect locking of thepivotal impeller wheel relative to the drive wheel in one or moreposition(s) relative to one another. As a result, the device accordingto the invention advantageously differs from the known devices inrequiring an enormously favorable material expense and productioneffort, so that the production costs of a camshaft adjusting device withsuch a locking system are increased only insignificantly by comparisonwith a camshaft adjusting device without a locking system.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described below with reference to two examples ofembodiment. In the appended drawings:

FIG. 1a shows the upper part of a cross section through a firstembodiment of a camshaft adjusting device configured according to theinvention;

FIG. 1b shows the lower part of a cross section through a secondembodiment of a camshaft adjusting device configured according to theinvention;

FIG. 2a shows the upper part of the section A—A in accordance with FIGS.1a and 1 b with the first embodiment of the camshaft adjusting deviceconfigured according to the invention;

FIG. 2b shows the lower part of the section A—A in accordance with FIGS.1a and 1 b with the second embodiment of the camshaft adjusting deviceconfigured according to the invention;

FIG. 3 shows a plan view of the lateral wall remote from the camshaft ofthe first embodiment of the camshaft adjusting device configuredaccording to the invention; and

FIG. 4 shows the enlarged partial section B—B in accordance with FIG. 2bthrough the peripheral wall of the second embodiment of the camshaftadjusting device configured according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1a and 1 b and FIGS. 2a and 2 b clearly show a device 1,configured as a pivotal impeller wheel adjusting device, for varying thevalve control times of an internal combustion engine, which comprises adrive wheel 2 configured as an outer rotor and drive-connected to acrankshaft (not shown) of the internal combustion engine and of apivotal impeller wheel 10 configured as an inner rotor and connected ina rotationally fixed manner to a camshaft 9 of the internal combustionengine. It is also apparent from FIGS. 1a and 1 b, in conjunction withFIG. 3, that the drive wheel 2 comprises a cavity 6 formed by aperipheral wall 3 and two lateral walls 4, 5, within which cavity fourhydraulic working spaces 8 are formed by four delimitation walls 7starting from the inside of the peripheral wall 3 and oriented towardthe longitudinal central axis of the drive wheel 2. FIGS. 2a and 2 badditionally show that the pivotal impeller wheel 10 likewise comprisesfour blades 12 disposed on the periphery of its wheel hub 11 and isinset into the cavity 6 of the drive wheel 2 in such a manner that eachblade 12 extends into a working space 8 of the drive wheel 2 and dividesthe latter into pairs of hydraulic pressure chambers 13, 14 working inopposition to one another. Clearly visibly here, the pressure chambers13, 14 are sealed off from one another by sealing elements 17 disposedbetween the free end surface 15 of each blade 12 of the pivotal impellerwheel 10 and the peripheral wall 3 of the drive wheel 2 so that thepressure chambers 13, 14, if selectively or simultaneously subjected tothe action of pressure by means of a hydraulic pressure medium, effect apivot movement or fixing of the pivotal impeller wheel 10 relative tothe drive wheel 2.

A further feature of the device 1 shown in the drawings is that afterthe internal combustion engine is switched off, its pivotal impellerwheel 10 can be mechanically coupled to the drive wheel 2, with a changeof volume of the pressure chambers 13, 14 of each hydraulic workingspace 8, in a preferred basic position for the starting of the internalcombustion engine, the device 1 illustrated being configured, by way ofexample, as a pivotal impeller wheel adjusting device mounted on aninput camshaft, whose pivotal impeller wheel can be mechanically coupledto the drive wheel, with minimization of the volume of a pressurechamber 13, in the basic position shown in FIGS. 2a and 2 b andcorresponding to a “late position” of the camshaft 9. In the device 1according to the invention shown, this mechanical coupling is effectedin that at least one of the sealing elements 17 between the pivotalimpeller wheel 10 and the drive wheel 2 of the device 1 issimultaneously configured as a locking element 18. In this context, itcan be clearly seen in the drawings that the sealing elements 17 forsealing off the pressure chambers 13, 14 of the device 1 are configuredas sealing strips disposed in each case within an axial groove 22 in thefree end surface 15 of each blade 12 of the pivotal impeller wheel 10and configured to be radially movable via supporting springs 23, andhaving an axial length corresponding to the width of the peripheral wall3 of the drive wheel 2 and a radial height corresponding toapproximately half the length of a blade 12 of the pivotal impellerwheel 10. Each of these sealing strips 17 configured as a lockingelement 18 is then movable in a conventional manner by a sprint element19 into a coupling position within a complementary seating 20 in thedrive wheel 2, which is hydraulically connected to the pressure mediumfeed 21 to a volume-minimized pressure chamber 13 of a hydraulic workingspace 8 of the device 1 in a manner such that when the internalcombustion engine is started, as a result of the subjection to theaction of pressure of the volume-minimized pressure chamber 13 of eachhydraulic working space 8 the seating 20 is simultaneously subjected tothe action of pressure and the sealing strip configured as a lockingelement 18 is moved hydraulically into an uncoupling position.

In a first embodiment of the device configured according to theinvention, shown in FIGS. 1a and 2 a, this is achieved in that only onesealing strip simultaneously configured as a locking element 18 isadditionally axially movable in a manner such that, in the couplingposition, it is in positive engagement, by its lateral surfaces 25oriented toward the lateral wall 4 of the drive wheel 2 in only onelocking position of the device 1, corresponding to the abovementioned“late position” of the camshaft 9, with a complementary seating 20. Itis apparent here from FIG. 3 that the complementary seating 20 isconfigured as a radial fixing groove 26, which is disposed in thevicinity of the delimitation wall 7 of the working space 8 of the drivewheel 2 divided by the blade 12 with the locking element 18 and ismachined into the lateral wall 4 of the drive wheel 2 remote from thecamshaft to extend radially to the longitudinal axis of the device 1.Similarly, it can be clearly seen that the radial fixing groove 26 has alength approximately corresponding to the height of the sealing stripsimultaneously configured as a locking element and is configured to berecessed over part of its length by a further pressure medium guidegroove 29, which opens at its end facing the longitudinal central axisof the device 1 into a pressure medium transverse groove 32 machined inthe lateral wall 4 of the drive wheel 2 remote from the camshaft. Thisradial fixing groove 26 is configured to be wear-resistant by partialhardening of the lateral wall 4 of the drive wheel 2 remote from thecamshaft, the non-recessed parts of the groove floor of the radialfixing groove 26 being provided as axial stop surfaces 30, 31 of thesealing strip in its coupling position. The pressure medium guide groove29 is moreover hydraulically connected via the pressure mediumtransverse groove 32 extending as far as the stop surface 38 of thedelimitation wall 7 to the pressure chamber 13, volume-minimized in thecoupling position of the pivotal impeller wheel 10, of the hydraulicworking space 8 of the drive wheel 2 in order to be able to uncouple thelocking element 18 hydraulically, as described initially.

Two helical compression springs, each disposed within an axial basicbore 33, 34 in the lateral surface 24 of the sealing strip facing thecamshaft, are provided as the spring element 19 for the axial movementof the sealing strip configured as a locking element 18 into itscoupling position and are each disposed within their basic bores 33, 34to enclose a guide pin 35, 36 which is in sliding spot contact with theinside of the lateral wall 5 of the drive wheel 2 facing the camshaft.These guide pins 35, 36 possess, at their ends facing the camshaft, across-sectional thickening which can be recessed in their basic bores inthe uncoupling position of the sealing strip and by means of which thehelical compression springs can be supported at one end on the floor ofthe basic bores 33, 34 and at the other at the transition surface tothis cross-sectional thickening.

In a second embodiment of the device 1 according to the invention, shownin FIGS. 1b and 2 b, by contrast, the radially movable arrangement ofthe sealing strips 17 in the axial grooves 22 in the end surfaces 15 ofthe blades 12 is used in such a way that, again, only one sealing stripsimultaneously configured as a locking element 18 is, in the couplingposition, in positive engagement, by its sealing surface 27 orientedtoward the peripheral wall 3 of the drive wheel 2 in, again, only onelocking position of the device 1, with a complementary seating 20. As isapparent from FIGS. 2b and 4, in this embodiment the complementaryseating 20 is configured as an axial fixing groove 28, which is machinedin the vicinity of the delimitation wall 7 of the hydraulic workingspace 8 into the inside of the peripheral wall 3 of the drive wheel 2divided by the blade 12 with the locking element 18 and is configured tobe wear-resistant by partial hardening of the peripheral wall 3 of thedrive wheel 2. FIG. 2b also indicates that the sealing surface 27 of thesealing strip simultaneously configured as a locking element 18 isslightly chamfered in the radial direction and is configured as apressure impact surface of the hydraulic pressure medium for theuncoupling position of the sealing strip. A separate pressure mediumfeed line 37 opens here into the widening gap between the sealingsurface 27 of the sealing strip and the groove floor of the axial fixinggroove 28, this separate pressure medium feed line 37, as is moreclearly apparent from FIG. 4, being configured as a bilateral edgechamfer of the peripheral wall 3 of the drive wheel 2. As a result ofthis edge chamfer, extending from the stop surface 38 of onedelimitation wall 7 of the hydraulic working space 8 to the axial fixinggroove 28, the axial fixing groove 28 is again hydraulically connectedto the volume-minimized pressure chamber 13 of the hydraulic workingspace 8 divided by the blade 12 with the locking element 18, so that thehydraulic uncoupling of the locking element 18 described initially isensured.

The spring element 19 for the radial movement of the sealing stripconfigured as a locking element 18 into its coupling position is, inthis second embodiment of the device 1 according to the invention,formed by the supporting spring 23 of the sealing strip indicated inFIG. 1a, which in the specific case is configured as a leaf spring andis supported at one end on the groove floor of the axial groove 22 forthe sealing strip and at the other end on the end surface 39 of thesealing strip facing the groove.

What is claimed is:
 1. A device for varying the valve control times ofan internal combustion engine, especially a camshaft adjusting devicewith a pivotal impeller wheel, having the following features: 1.1 thedevice (1) comprises a drive wheel (2) configured as an outer rotor anddrive-connected to a crankshaft of the internal combustion engine, whichdrive wheel (2) comprises a cavity (6) formed by a hollow cylindricalperipheral wall (3) and two lateral walls (4, 5), 1.2 within the cavity(6) of the drive wheel (2) at least one hydraulic working space (8) isformed by two delimitation walls (7) starting from the inside of theperipheral wall (3) and oriented toward the longitudinal central axis ofthe drive wheel (2), 1.3 the device (1) further comprises a pivotalimpeller wheel (10) configured as an inner rotor and connected in arotationally fixed manner to a camshaft (9) of the internal combustionengine and inset into the cavity (6) of the drive wheel (2), 1.4 thepivotal impeller wheel (10) has on the periphery of its wheel hub (11)at least one radially disposed blade (12), which extends into a workingspace (8) of the drive wheel (2) and divides the latter into pairs ofhydraulic pressure chambers (13, 14) working in opposition to oneanother, 1.5 the pressure chambers (13, 14) are sealed off from oneanother by sealing elements (17) disposed at least between the free endsurface (15) of each blade (12) of the pivotal impeller wheel (10) andthe peripheral wall (3) of the drive wheel (2), 1.6 the sealing elements(17) are preferably configured as sealing strips disposed in each casewithin an axial groove (22) in the free end surface (15) of each blade(12) of the pivotal impeller wheel (10) and radially movable viasupporting springs (23), 1.7 the pressure chambers (13, 14), whenselectively or simultaneously subjected to the action of pressure bymeans of a hydraulic pressure medium, effect a pivot movement or fixingof the pivotal impeller wheel (10) relative to the drive wheel (2) andhence of the camshaft (9) relative to the crankshaft, 1.8 when theinternal combustion engine is switched off, the pivotal impeller wheel(10) can be mechanically coupled to the drive wheel (2), with a changeof volume of the pressure chambers (13, 14) of each hydraulic workingspace (8), in a preferred basic position for the starting of theinternal combustion engine, 1.9 the mechanical coupling is effected by alocking element (18) disposed on the pivotal impeller wheel (10) or onthe drive wheel (2) and movable by a spring element (19) into a couplingposition within a complementary seating (20) in the drive wheel (2) orin the pivotal impeller wheel (10), 1.10 the complementary seating (20)of the locking element (18) is hydraulically connected to the pressuremedium feed (21) to at least one pressure chamber (13 or 14) of ahydraulic working space (8) of the device (1), 1.11 when the internalcombustion engine is started, as a result of the subjection to theaction of pressure of a pressure chamber (13 or 14) of each hydraulicworking space (8) the seating (20) of the locking element (18) issimultaneously subjected to the action of pressure and moves the latterhydraulically into an uncoupling position, 1.12 at least one of thesealing elements (17) between the free end surface (15) of each blade(12) of the pivotal impeller wheel (10) and the peripheral wall (3) ofthe drive wheel (2) of the device (1) is simultaneously configured as alocking element (18) for the mechanical coupling of the pivotal impellerwheel (10) to the drive wheel (2) of the device (1), 1.13 the sealingstrip simultaneously configured as a locking element (18) in thecoupling position is in positive engagement, by its sealing surface (27)oriented toward the peripheral wall (3) of the drive wheel (2) in one ormore locking position(s) of the device (1), with, in each case, oneaxial fixing groove (26) configured as a complementary seating (20) inthe inside of the lateral wall (3) of the drive wheel (2).
 2. The deviceas claimed in claim 1, wherein at least the sealing strip simultaneouslyconfigured as a locking element having an axial length corresponding tothe width of-the peripheral wall of the drive wheel and a radial heightcorresponding to approximately half the length of a blade of the pivotalimpeller wheel.
 3. The device as claimed in claim 1, wherein the sealingstrip simultaneously configured as a locking element is preferably inlatching connection with the drive wheel in only one locking position ofthe device, its axial fixing groove preferably being machined into theinside of the peripheral wall of the drive wheel in the vicinity of oneof the two delimitation-walls of the hydraulic working space of thedrive wheel divided by the blade with the locking element.
 4. The deviceas claimed in claim 3, wherein the inside of the peripheral wall of thedrive wheel is of wear-resistant, hardened configuration at least in theregion of the axial fixing groove, or the region of the axial fixinggroove is formed by a separate, prefabricated insert component made froma wear-resistant metal.
 5. The device as claimed in claim 1, whereinsealing surface of the sealing strip simultaneously configured as alocking element is slightly chamfered in the radial direction and isconfigured as a pressure impact surface of the hydraulic pressure mediumfor the uncoupling position of the sealing strip, a separate pressuremedium feed line being disposed to open into the widening gap betweenthe sealing surface of the sealing strip and the groove floor of theaxial fixing groove, this separate pressure medium feed line beinghydraulically connected to a pressure chamber of the hydraulic workingspace divided by the blade with the locking element.
 6. The device asclaimed in claim 5, wherein the separate pressure medium feed line tothe sealing surface of the sealing strip configured as a locking elementis preferably configured as a unilateral or bilateral chamfering of theperipheral wall of the drive wheel or as a pressure medium guide groovemachined into the inside of the peripheral wall and is disposed toextend from the stop surface of one of the delimitation walls of thehydraulic working space divided by the blade with the locking element asfar as the axial fixing groove.
 7. The device as claimed in claim 1,wherein the supporting spring of the sealing strip, preferablyconfigured as a chimney spring or leaf spring is provided as the springelement for the radial movement of the sealing strip configured as alocking element into its coupling position and is disposed to besupported at one end on the groove floor of the axial groove for thesealing strip in the free end surface of the blade of the pivotalimpeller wheel and at the other end on the end surface of the sealingstrip facing the groove.